Traumatic life events may directly increase your risk for dementia

By Neha MathurReviewed by Lily Ramsey, LLMSep 26 2023

In a recent article published in BMC Geriatrics, researchers examined the association between traumatic life events (TLE) and the risk of all-cause dementia in individuals aged ≥60. 

Studies included in the review encompassed outcomes of 276,570 participants with median age ranging from 50.3 to 77 years and a follow-up time ranging between two to 37 years (average = 9.5 years). 

Study: Traumatic life events and risk for dementia: a systematic review and meta-analysis. Image Credit: fizkes/Shutterstock.com

Background

Studies have suggested that experiencing TLEs, such as actual/threatened death, injury, and sexual violence, might contribute to dementia risk.

Globally, the care and treatment cost of dementia is estimated to be around one trillion USD annually. Given that >150 million people will be living with dementia by 2050, it has become crucial to identify and target modifiable risk factors that could prevent dementia.

Systematic reviews have reported an association between PTSD and dementia; however, none, so far, have examined the same between dementia risk and TLE.

It is crucial to understand whether TLE identified during PTSD diagnosis or diagnosed separately is a risk factor for dementia to help find interventions to mitigate dementia risk and prevent/delay its onset.

About the study

In the current study, researchers carried out a systematic review and generic inverse variance random effects meta-analysis to estimate TLE's impact on dementia risk, which they presented as risk, odds, and hazards ratios (HRs). The team utilized the Life Events Checklist for DSM-5 (LEC-5) criterion to identify TLE.

All included studies were original research articles published in peer-reviewed journals with case-control and cohort study designs that specified dementia diagnosis as an outcome in a study population of a minimum of 60 people.

All were related to all-cause dementia, with varying severities, and across all recruitment settings but excluded early onset dementia, having different etiology. They collected information regarding various forms of TLE (e.g., childhood trauma) from participants, their informants, or medical records.

The search strategy involved searching PsychINFO, Embase, and MEDLINE databases from inception until 20 April 2022 using keywords for "dementia,” "risk," and "traumatic events."

The team exported all retrieved studies to Covidence systematic review software. Next, two reviewers independently screened all articles at all stages, adhering to rigorous inclusion and exclusion criteria.

They used the Newcastle–Ottawa Scale for quality assessment of the studies and evaluated non-randomized epidemiological studies (NOS) having three domains: selection, comparability, and outcome. Further, they used a funnel plot to assess publication bias in the included studies.

The researchers classified a study as good if it had ≥3 and ≥1 stars in the selection and comparability domains and ≥ 3 stars in the outcome domain. Likewise, they also classified studies as 'Fair' and 'Poor' quality. 

Finally, the team meta-analyzed all studies and then conducted sub-analyses, stratifying by type of trauma, and used I2-statistic to measure heterogeneity. In sensitivity analyses, they included studies reporting HRs and having high quality.

Results

The reviewers screened 3,523 studies and identified 29 research papers for full-text screening. Finally, they included seven studies in the meta-analysis; one was a cross-sectional study, three were prospective cohort studies, and three were retrospective cohort studies.

Pooled results from the meta-analysis of seven studies demonstrated that TLE increased the risk of all-cause dementia (HR = 1.21). The results showed significant heterogeneity (I2 = 78%).

Further, the authors noted that trauma subtypes, like trauma occurring in war and childhood, also increased the risk of all-cause dementia (pooled HR = 1.28), albeit based on fewer studies (n=3). These results also showed significant heterogeneity (I2 = 75%). 

Conclusions

Overall, the current study recognized TLEs as potentially modifiable risk factors associated with increased risk of all-cause dementia.

Understanding the mechanisms by which TLEs increase susceptibility to dementia could help devise targeted interventions that reduce the effect of trauma, including PTSD, on dementia.

Future studies should investigate the impact of TLE-specific factors, such as chronicity and severity, and individual factors, such as age effect and association of TLEs with dementia subtypes.